Structural performance of double-wall steel insulation silo with multiple bolted joints

The purpose of this study is to study the structural behaviors of a double-wall insulated steel silo under a storing loading with concentric discharge. Current silo structures are predominantly single-wall thin-wall silos, which have a lack of thermal insulation capability. This innovative double-wall silo consists of internal and external walls with multiple bolt connections and ring beams, which can not only provide effective insulation but also enhance the stability and bearing capacity of the structure. However, the structural performance and bearing mechanism of the double-wall silo are not well understood. In this study, a 1000-t double-wall steel silo designed according to specifications was computationally studied via a set of analyses using ANSYS, including linear bifurcation, linear elastic, geometric nonlinear, geometrically and materially nonlinear, and geometrically and materially nonlinear with imperfections. These analyses revealed a cooperative bearing mechanism of the silo walls. In particular, 2/3 of the vertical friction is borne by the external wall, while the majority of the horizontal pressure is borne by the internal wall. The results also highlighted the stress distribution of the silo walls under a storing load. The results of a nonlinear analysis indicated that the failure mode was an “elephant's foot” deformation if the material plasticity was included. Compared with that without material plasticity, the studied silo exhibited plasticity-dominant behavior. The double-wall silo has advantages over the single-wall silo such as better insulation and structural performance.